You understood correctly - the RadEditor for MOSS Lite version is primarily intended as a cross-browser alternative to the default SharePoint 2007 rich text editor. It has limited functionality and is missing some of the normal RadEditor features.
The Full featured RadEditor for MOSS is available to all customers, who have a license for the normal RadEditor control for ASP.NET - http://www.telerik.com/products/sharepoint/editor-for-asp.net.aspx
This means that there is no additional cost over that, which you have to pay for the RadEditor for ASP.NET. If you have a licence for the normal editor, you will be able to download the full featured MOSS version from the main RadEditor downloads page.
the Telerik team